Other Consolidated Financial Statement Detail (Details Textual) € in Millions, $ in Millions	1 Months Ended	3 Months Ended										12 Months Ended
	Feb. 28, 2015 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 EUR (€)	Jun. 30, 2013 USD ($)
Business Acquisition [Line Items]
TECFIDERA litigation settlement and license charges												$ 454.8	$ 0.0	$ 0.0
Increase to goodwill												1,026.9	908.1
Accrued construction in progress		$ 134.0				$ 87.9						134.0	87.9
Contingent consideration obligation												0.0	274.5
Prepaid taxes		817.0				550.6						817.0	550.6
Product, net		2,502.9	$ 2,539.6	$ 2,466.0	$ 2,309.4	2,425.9	$ 2,391.7	$ 2,198.6	$ 2,172.3			9,817.9	9,188.5	8,203.4
Accrued expenses and other long-term deferred revenue		722.5				$ 905.8						722.5	905.8
Solothurn
Business Acquisition [Line Items]
Accrued construction in progress		100.0										100.0
Convergence Pharmaceuticals
Business Acquisition [Line Items]
Contingent consideration obligation	$ 274.5
TECFIDERA
Business Acquisition [Line Items]
Product, net												3,968.1	3,638.4	$ 2,909.2
TECFIDERA | Fumapharm AG
Business Acquisition [Line Items]
Increase to goodwill												1,200.0	$ 900.0
TECFIDERA | Eleven billion | Fumapharm AG
Business Acquisition [Line Items]
Increase to goodwill												300.0
Cumulative sales level		11,000.0										11,000.0
ITALY
Business Acquisition [Line Items]
Proposed settlement		$ (37.4)									$ (30.7)	(37.4)				$ (33.3)
Reimbursement Limit Stated In Resolution										24 days	24 days
Loss contingency accrual																$ 15.4
Loss contingency, adjustment related to claim amount, percent																50.00%
Product, net										$ 53.5		$ 42.0
Accrued expenses and other long-term deferred revenue | €															€ 79